CVE-2018-6551: gnu glibc Integer Overflow or Wraparound
Vulnerability summary
CVE-2018-6551 is a critical (CVSS 9.8) Integer Overflow or Wraparound vulnerability in gnu glibc. EPSS estimates a 2.21% chance of exploitation in the next 30 days, higher than 82.6% of scored vulnerabilities.
Severe, CVSS 9.8 (NVD); no exploitation reported by the 5 checked sources; EPSS 2% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 3 · Related 2Timeline
- 02-02-2018PublishedVulnerability first disclosed.
- 05-08-2024Last modifiedVulnerability information updated.
Description
The malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386, did not properly handle malloc calls with arguments close to SIZE_MAX and could return a pointer to a heap region that is smaller than requested, eventually leading to heap corruption.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
2.21%
Chance of exploitation in the next 30 days
Percentile
83%
Versus all other CVEs
30-day change
Increase +0.02 pp
From 2.19% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Debian1 product
- glibc< 2.27-1
Gnu1 product
- glibc≥ 2.24, ≤ 2.26
Ubuntu1 product
- glibc< 2.27-3ubuntu1
3 vendors · 3 products
References
7 links- sourceware.org/bugzilla/show_bug.cgi?id=22774X Refsource CONFIRMIssue TrackingMailing ListThird Party AdvisoryREPORT
- security.netapp.com/advisory/ntap-20190404-0003/X Refsource CONFIRM
